1. Field of the Invention
The present invention relates to semiconductor chips. More specifically, the present invention relates to a method and an apparatus for automatically detecting and correcting mechanical misalignment of a semiconductor chip.
2. Related Art
During the process of manufacturing a computing system, a semiconductor chip is typically integrated into a computing system at a desired location on a printed circuit board (PCB) or on some other type of chip carrier module. Typically, the position of a chip on the PCB or the carrier module can affect chip performance. Even a small deviation from this desired chip location due to a mechanical misalignment of the chip can seriously degrade chip performance or even cause system failure.
Typically, the location of a chip is fixed because the chip is mechanically soldered or wire-bonded onto the PCB or carrier. It is then assumed that the chip position will not change with respect to: surrounding signal lines (in the PCB or carrier), neighboring chips, and other system components. Unfortunately, even when the chip is mechanically attached to the PCB or carrier, a mechanical misalignment can still occur due to environment changes, such as a temperature variation which induces thermal expansion or contraction of the chip and/or the PCB or carrier. Furthermore, mechanical vibration of the PCB or carrier to which the chip is attached can also cause mechanical misalignment of the chip. Yet another example involves a system comprising a chip-optical fiber assembly, which typically requires even higher mechanical alignment precisions during the attachment between the chip and the optical fiber, wherein a sub-micron misalignment can cause significant light coupling losses.
As the integration and packaging densities continue to increase, the magnitude of above mechanical misalignments have become more significant in comparison to circuit dimensions or size of the fibers. Consequently, significantly more precise chip alignment is required.
Mechanical misalignment also occurs due to aberrant movement of a chip when the chip is mechanically floating in relation to other chips. For example, in a system that supports proximity communication through capacitive coupling between neighboring chips, the effectiveness of the communication relies on precise alignment between neighboring chips, which are proximate to each other, but not mechanically attached to each other.
Existing techniques for dealing with alignment problems generally involve time-consuming manual alignment operations. Furthermore, these alignment operations require the system to be turned off and disassembled, which can adversely affect system availability.
Hence, what is needed is a method and an apparatus for automatically detecting and correcting misalignment between semiconductor chips in order to improve system performance.